Page 17 - index
P. 17
Iris Diseases
Chuck Chapman
Scorch:
A disease that slowly kills Iris plants. They
slowly turn brown over a time period, with the
rhizomes remaining hard. A prevention from death
can involve cutting the rhizome into sections.
Thus an infected clump will usually have one
part survive. It is necessary to dig up the clump to
examine it closely.
The Iris borer can also eat out a clump and the
leaves will also turn brown from the tips down.
This can be quite fast as the borer is in the rhizome
before this effect is noticed and it proceeds quickly.
If you dig up the plant you fnd a chewed out area
(usually quite large) and sometimes the borer is still
present. Soft Rot can also cause similar problems.
In this case when you dig up the plant you will fnd
a mushy plant, or what remains of the rhizome.
A recent suggestion for cure of scorch involves heating the plant to 104 degrees F for
a few days. This seems to kill the scorch, leaving the plant unharmed. This can be done
with a covering over the plant, but care must be taken that the temperature doesn’t get too
hot and cook the plant.
Borer:
An insect that can be very
damaging to the Iris. It is not found in
Western Canada or USA, but in mid
and eastern sections of Canada and the
USA it can be very devastating.
The moth lays its eggs late Fall
and they overwinter on the leaves.
They hatch in early spring, around
the time the daffodils come into
bloom. They are initially near the
top of the leaves, usually where the
leaves separate from each other. They
gradually chew their way down the plant and three weeks after the TB’s stop blooming,
they are in the rhizomes. About the end of August (here in southern Ontario) they have
left the plant and are in metamorphosis.
Canadian Iris Society Newsletter 15
Chuck Chapman
Scorch:
A disease that slowly kills Iris plants. They
slowly turn brown over a time period, with the
rhizomes remaining hard. A prevention from death
can involve cutting the rhizome into sections.
Thus an infected clump will usually have one
part survive. It is necessary to dig up the clump to
examine it closely.
The Iris borer can also eat out a clump and the
leaves will also turn brown from the tips down.
This can be quite fast as the borer is in the rhizome
before this effect is noticed and it proceeds quickly.
If you dig up the plant you fnd a chewed out area
(usually quite large) and sometimes the borer is still
present. Soft Rot can also cause similar problems.
In this case when you dig up the plant you will fnd
a mushy plant, or what remains of the rhizome.
A recent suggestion for cure of scorch involves heating the plant to 104 degrees F for
a few days. This seems to kill the scorch, leaving the plant unharmed. This can be done
with a covering over the plant, but care must be taken that the temperature doesn’t get too
hot and cook the plant.
Borer:
An insect that can be very
damaging to the Iris. It is not found in
Western Canada or USA, but in mid
and eastern sections of Canada and the
USA it can be very devastating.
The moth lays its eggs late Fall
and they overwinter on the leaves.
They hatch in early spring, around
the time the daffodils come into
bloom. They are initially near the
top of the leaves, usually where the
leaves separate from each other. They
gradually chew their way down the plant and three weeks after the TB’s stop blooming,
they are in the rhizomes. About the end of August (here in southern Ontario) they have
left the plant and are in metamorphosis.
Canadian Iris Society Newsletter 15
